Here's a quote to give you a flavour:
During an otherwise mundane train journey in 2004, I heard a fantastical mechanical sound. The train turned along a curved length of track, causing dense creaking of multiple loose panels, all modulated chaotically by carriage motion until an inter-carriage door slammed, obliterating the interactions that gave birth to the fleeting sonic marvel. Language doesn’t do this marvel justice. The experience compelled me to acoustically reproduce the sound—how difficult could it be? But after eight years it still eludes me. I call near-irreproducible acoustic flourishes like this miraculous agitations.
I wonder if these sounds aren't heard only in the listener's head -- a fleeting sound which connotes a melody? There's an interesting harmonic phenomena mentioned in this video.
The idea of acoustic synthesis that Dan Wilson mentions in the article is cool and something I've thought around but not at the depth that he's explored. In previous years I've been enamoured with 'the wires' for their synthesiser-like noises and was really excited when I found that by playing drums next to them I could make them respond to the tempo I was pounding.
The idea of creating machines which generate noises that have musical qualities is appealing to me. I've got this idea for one that I'm hoping to develop but I'm going to try out this thaumaturgy thing that Dan mentioned, for now.